Replies to post #42041 on Sulja Bros. Building Supplies, Ltd (SLJB)

[pennyjunkie]

yeah...
Rubberized Asphalt Concrete (RAC) incorporates ground tire (crumb) rubber into the hot mix. Crumb rubber is ground or granulated rubber particles, which are derived from auto, light truck or other sources that use a high content of natural rubber. The wet process is typically used in rubberized asphalt within the State of California. The wet process mixes the rubber with the binder (80% asphalt cement / 20% crumb rubber) in a field blending unit prior to introduction at the hot mix plant. Caltrans began experimenting with rubberized asphalt produced by the "wet process" in the 1970's and developed design criteria using roadway deflection testing that resulted in thinner overlay courses than conventional asphalt concrete. Research has shown that 4" of conventional asphalt can be replaced with 2" of rubberized asphalt to achieve the same fatigue life. In the early 1990s, Caltrans testing confirmed the reduced thickness design of a gap-graded mix and received approval from the Federal Highway Administration. The stated advantages of Rubberized Asphalt Concrete are as follows:

1. Rubberized Asphalt Concrete is highly skid-resistant, quieter and resists shoving and rutting if a gap-graded mix is used.
2. Rubberized asphalt concrete is environmentally friendly. A two-inch resurfacing project can use approximately 2,000 waste tires per lane mile.
3. Rubberized asphalt concrete provides excellent long-lasting color contrast for striping and marking.
4. Rubberized asphalt concrete provides a long-lasting, durable pavement that resists reflective cracking.
5. Rubberized asphalt can be placed using conventional paving equipment and methods

Although research has shown that a thinner section can be placed and may ultimately last longer than conventional asphalt concrete, rubberized asphalt concrete does cost more per ton to produce due to the ground rubber and other ingredients as well as the cost of bringing in a portable blending unit to the hot mix plant. Rubberized asphalt can also be produced using a terminal blended process where the crumb rubber is added at the refinery or asphalt cement terminal. The advantage being that no specialized costly rubberized blending plant is required by the hot mix producer. The binder can be shipped to the hot mix plant just as a typical binder would be. This method offers a substantial cost savings over the wet process.

Graniterock recently produced hot mix asphalt using a terminal blended rubber for a running track at a local high school in Aptos, CA. This binder, supplied by the refinery, was the first ever use of a RAC-15 product conforming to ASTM-D6114 Asphalt-Rubber Binder specifications within the State of California. ASTM stands for American Society of Testing and Materials. The school applied for and was awarded a monetary grant by the California Integrated Waste Management Board for using recycled materials (i.e. rubberized asphalt concrete).

Graniterock has a proven track record of using Rubberized Asphalt Concrete to enhance the performance of asphalt pavements in certain applications. If you would like to learn more about your binder choices, please call Graniterock’s sales office at 831-768-2380.